1. Field of the Invention
The present invention is directed to a work vehicle. In more particular, the present invention is directed to, but not exclusively, a work vehicle that includes an electronic control unit that controls on-board electric components, a first battery that is charged using electric power from an on-board electric generator, and a second battery that is charged from an external electric power source via a charger.
The present invention is also directed to a display device for a work vehicle. In more particular, the present invention is directed to, but not exclusively, a display device for a work vehicle that includes a liquid crystal display provided with a plurality of display units that display information related to an engine, and a display electronic control unit that controls the operations of the liquid crystal display.
2. Description of the Related Art
[1] First Related Art
In recent hybrid work vehicles, a battery for supplying electric power to e.g. a travel oriented electric motor, may be charged with electric power from an external electric power source (e.g. see JP 2012-232724A, in particular, paragraphs 0021 and 0022 and FIGS. 1 and 5).
With a plug-in hybrid work vehicle including first and second batteries as described above, if the output voltage of the first battery is low when charging the second battery from an external electric power source, the output voltage of the first battery may fall below a reference voltage value that is necessary for starting an engine during charging of the second battery. If the output voltage of the first battery falls below the reference voltage value, the engine can no longer be started using electric power from the first battery after charging the second battery from the external electric power source. Furthermore, when an on-board electric generator is an alternator that operates on power from the engine, the first battery can no longer be charged using electric power from the alternator.
In view of the above, there is a demand to prevent the possibility that the output voltage of the first battery may fall below the reference voltage value after charging the second battery from the external electric power source.
[2] Second Related Art
Some of these work vehicles include a display device provided with an approximately four-inch liquid crystal display having a plurality of display units (display areas) for displaying engine-related information, such as an engine revolution display area that displays the number of engine revolutions, an hour meter display area that displays an accumulated period of engine operation, a coolant temperature area that displays a temperature of an engine coolant, and a fuel gauge area that displays a remaining amount of fuel to be supplied to the engine (e.g. JP 2013-252747A, in particular, paragraphs 0020, 0041 and 0042 and FIGS. 6 and 11).
Hybrid work vehicles developed in recent years include not only an engine, but also a motor generator, as its power sources. In such hybrid work vehicles, a display device needs to display not only information related to the engine, but also information related to the motor generator. This need can be fulfilled by increasing the size of a liquid crystal display along with an increase in the amount of information to be displayed. However, increasing the size of the liquid crystal display triggers an increase in the size of the display device and a significant rise in cost. Meanwhile, the size of each display unit can be reduced along with an increase in the amount of information to be displayed. However, this triggers a reduction in the visibility of information displayed on each display unit of the liquid crystal display.
In view of the above, there is a demand to develop a display device that can display not only information related to an engine, but also information related to a motor generator, without triggering an increase in the size of a display device and a significant rise in cost, or a reduction in the visibility of information to be displayed.